package cn.bo.cloud.common.core.encrypt;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Md5Encrypt {
    /**
     * Used building output as Hex
     */
    private static final char[] DIGITS = { '0', '1', '2', '3', '4', '5', '6',
            '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };

    /**
     * 对字符串进行MD5加密
     * @param text 明文
     * @param charSet 字符编码
     * @return 密文
     */
    public  static final String encrypt(String text, String charSet) {
        MessageDigest msgDigest = null;
        try {
            msgDigest = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            throw new IllegalStateException("System doesn't support MD5 algorithm.");
        }
        //charSet为null时，不重新编码
        if(charSet != null){
            try {
                msgDigest.update(text.getBytes(charSet)); //注意该接口是按照utf-8编码形式加密
            } catch (UnsupportedEncodingException e) {
                throw new IllegalStateException("System doesn't support your  EncodingException.");
            }
        }

        byte[] bytes = msgDigest.digest();
        return new String(encodeHex(bytes));
    }

    /**
     * 对字符串进行MD5加密  默认为UTF-8编码
     * @param text 明文
     * @return 密文
     */
    public  static final String encrypt(String text) {
        return encrypt(text, "UTF-8");
    }

    private static final char[] encodeHex(byte[] data) {
        int l = data.length;
        char[] out = new char[l << 1];
        // two characters form the hex value.
        for (int i = 0, j = 0; i < l; i++) {
            out[j++] = DIGITS[(0xF0 & data[i]) >>> 4];
            out[j++] = DIGITS[0x0F & data[i]];
        }
        return out;
    }
}
